81722400 has 144 divisors (see below), whose sum is σ = 281794464. Its totient is φ = 20500480.

The previous prime is 81722393. The next prime is 81722413. The reversal of 81722400 is 422718.

It is a Harshad number since it is a multiple of its sum of digits (24).

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 39799 + ... + 41801.

It is an arithmetic number, because the mean of its divisors is an integer number (1956906).

Almost surely, 2^81722400 is an apocalyptic number.

81722400 is a gapful number since it is divisible by the number (80) formed by its first and last digit.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 81722400, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (140897232).

81722400 is an abundant number, since it is smaller than the sum of its proper divisors (200072064).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

81722400 is a wasteful number, since it uses less digits than its factorization.

81722400 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2043 (or 2030 counting only the distinct ones).

The product of its (nonzero) digits is 896, while the sum is 24.

The square root of 81722400 is about 9040.0442476793. The cubic root of 81722400 is about 433.9573389937.

The spelling of 81722400 in words is "eighty-one million, seven hundred twenty-two thousand, four hundred".